This Discussion will foster an examination of molecular genetic manipulations as they reveal physical and structural properties of proteins. Basic difficulties will be confronted, such as the structures of newly created species, the innovative use of mutagenesis to test specific hypotheses, and modeling built on computation or computer graphics as compared with the need for more accurate three-dimensional molecular structures. Proposed topics for this Discussion include gap junctions; acetylcholine receptors; ion-coupled transporters; bacterial chemotaxic receptors; rhodopsin and bacteriorhodopsin; sodium, potassium, and calcium channels; the bacterial flagellar "motor"; receptors and other membrane-spanning or lipid-linked proteins; protein design and engineering; protein folding; and protein/polypeptide insertion. The Biophysical Discussions employ a unique format whereby (a) the complete texts of all contributions are circulated in advance to all participants; (b) the meeting time is devoted solely to discussions, not formal presentations; (c) a transcription of the plenary debate is incorporated into the final proceedings volume. The Organizers of the Discussion hope that bringing together scientists working in the topical areas will raise important new questions, resolve some research controversies, and produce a definitive volume on the subject of Biophysics and Recombinant DNA, a topic of great current interest in the further development and refinement of biotechnology. The latter development has enabled the pharmaceutical industry and individual biotechnology companies to produce for clinical applications adequate amounts of human hormones, growth factors, biological modifiers, and other therapeutic agents not otherwise available.